The Trailside Killer of San Francisco
Between December 1968 and July 1969, a decade earlier than the Trailside Killings, a man shot two couples in Vallejo, California, on two separate occasions, and called to take credit for them. One young man had survived to give a description. Then the editors of three San Francisco papers each received part of a strange letter claiming to be from the Vallejo killer. He had used too much postage and his message consisted of a printed cryptogram composed of symbols and signed with a crossed-circle symbol. One had to put them all together to crack the code, which a local teacher, after painstaking work, managed to do. Its author was clearly playing a sadistic game, as he described his joy in killing people and his intention to keep doing so.
Thus began a cat-and-mouse game by "the Zodiac," as he called himself. Then he attacked a third couple. On September 27, 1969, Cecelia Ann Shepard and her friend, Bryan Hartnell, were picnicking at Lake Berryessa, where a man wearing a black executioner's hood approached them. He stabbed them, attacking the girl repeatedly, and afterward called the police to report it. He struck again, two weeks later, killing cab driver Paul Stine. Soon after, the Chronicle received a letter with a torn piece of Stine's shirt. Yet no leads proved productive, and there was speculation that this same killer had been responsible for the murder of a young woman in another town as well. The Zodiac kept in sporadic contact with the SFPD and the Chronicle, but his killing seemed to end with seven victims, despite more extravagant claims —and threats — on his part.
Many different suspects were developed, but none checked out. The case proved to be one of the rare times when a serial murderer appeared to be quite clever and well-educated, making his crimes into a layered series of games. That he seemed to withdraw and lie low proved disturbing, because if he remained at large, he could always start up again, there or elsewhere. Douglas suggested that he might have been arrested for something, which had kept him from acting. For all anyone knew, this was the same person, freshly released, although the MO was certainly different. No one was calling to take credit for these murders, nor offering any codes.
Winter passed without further mishaps that anyone knew of (they would later learn this was not the case), but the police were busy with their investigation. Still, they had no leads. Around this time, the new art of profiling got some play. Graysmith is dismissive, but John Douglas actually had something interesting to say.